Process of treating soybean and similar glyceride oils



Patented Oct. V, i947 I uni OF TREATING SOYBEAN D GLYCIERIIDE E8 Lloyd F. Henderson, Reading, and Louis Ell.

Libby, Boston,

Mass'.,

assignors to Lever 8 Brothers Company, (iambridge, Mass.,'a cor-v poration of Maine No Drawing. Application September 11, 1944,

Serial No. 553,664

This invention relates color forming materials. The use of oil and fat stocks which contain color imparting materials, or materials which develop a color when the oil or fat is made into soap, are undesirable because a white soap has particular appeal to the user. For this reason the art has developed numerous processes from which light soaps can be made from color and potential color imparting materials.

1 With this desire in the art for white soaps and with dwindling supplies of high grade stocks ordinarily used in making such soaps, it has become necessary to consider other oils and fats as raw. materials.

. One such oil that. is becoming available in larger quantities is soybean oil. When this oil,

either in its original state or when hardened by.

hydrogenation, is used for making soap, a bright pink or red color develops on the surface after to a process of treating oils and fats to remove color forming ingredients the finished soap product has been exposed to the atmosphere, even for a short time. WhiIe this color under some conditions may not be permanent, nevertheless, on extended storage, it changes to a yellow, which is often somewhat more intense than the original pink color. This property of soybean oil has seriously mitigated against its use in making white soap This characteristic of soybean oil has been the subject of much investigation, and it has been ascertained that the conventional methods of re,- fining and bleaching oils, such as with a caustic solution, and with bleaching earths, are not effective for removing the constituent causing the pink coloration. I

Hydrogenation of soybean oil, even to complete saturation; fails'to destroy the bodies responsible for the development of the pink color in soap. This is indeed surprising, inasmuch as hydrogenation is known to destroy the materials which are responsible for the characteristic odor of soybean oil. Other reducing agents, such as a treatment of hardened soybean oil with acids, sodium hydrosulflte, sulfur dioxide, or formaldehyde sulfoxylates are equally ineffective. oxidizing treatments, which are not so harsh as to destroy 17 Claims. (on. 260-420)- the glyceride stock, are not successful in removing the color forming ingredients.

.The chemical nature or the constituents which cause the development of the pink color are not definitely known. Extensive research has. been done in an efiort to determine the unique constituents of soybean oil which are responsible for its peculiar color and'odor characteristics, but with little success.

It is an object of our invention to provide a process for treating soybean and similar oils to eliminate the color forming bodies therefrom so that the oils may be made into a white soap.

' A further object of our invention is the provision of a process which requires a minimum of readily available treating agents and which can be carried out with convenient processing operations and with existing plant equipment.

We have discovered that if an oil or fat, such as hardened or unhardened soybean oil, is treateg with formaldehyde or a formaldehyde polymer i the presence of an acid catalyst, the treated oil has a marked improvement in color itself and can be made into white soap which does not develop a characteristic color 'on' standing.

Without wishing to limit our invention to any theory of the chemistry involved, since the invention may be practiced to achieve the desirable results in accordance with the disclosure herein, the following explanation, however, mayfbe of interest. Many of the impurities in soybean and other vegetable glyceride oils are thought to be in the nature of aromatic phenols containing one or more benzene rings. These phenolic impuri ties usually are not strongly colored but may be readily oxidized to quinones, which are colored.

It is our thought that perhaps these, phenols or qulnones in the presence of an acid catalyst con= dense with an aldehyde to form materials of a for about one hour at a temperature of Cr resinous nature which can be removed from the oil.

In order that the invention and the method of practicing it may be better understood, the following example of a commercial embodiment is given, after which isindicated the equivalents The temperature is then brought up to C.

and about 2% of an acid-activated bleaching earth is added and the mixture is agitated for about 15 minutes. Following this, sufficient calcium carbonate is added to neutralize any remaining acid. The oil is cooled slightly, and is filtered while still in a liquid form. It is then ready for use in soap making. The oil thus treated may be made into soap, in accordance with any of the conventional soap making methods, and will be found to possess a white color.

As contrasted with this treatment, and as showing that an acid treatment is not effective, refined, bleached and hardened soybean oil was treated with 0.5% concentrated sulfuric acid, at a temperature of 70 C. for 1 hour, following which the oil was settled and the acid withdrawn.

The oil was then bleached with 6% of an acidactivated bleaching earth at about 100 C. The treated soybean oil was then made into soap. Although larger amounts of acid and bleaching earth were used in treating the oil, the soap was found to have a bright pink color. Similarly the treatment with formaldehyde alone is not effective' in eliminating the color forming bodies, and samples of soybean oil treated with paraformaldehyde alone and then bleached and filtered developed a pink color when made into soap.

Another oil which develops a pink color when made into soap, and which is admirablyir'nproved by the invention, is linseed oil. Castor oil also produces a soap which develops the same pink color, although it is used to a relatively small extent in soap making. Cottonseed oil presents a similar problem for use in soap making, although the original color of the soap made from this oil is yellow rather than pink. The problem arises more or less in connection with a wide variety of vegetable oils and the process of the invention can be used to treat any glyceride vegetable oil or fat. The process, however, may not produce a result in the case of every oil that is so striking as to justify the treatment of these oils by other than conventional methods. The invention assumes particular significance in the treatment of hardened and unhardened soybean and linseed oils where the condition is particularly aggravated and where large amounts of the oils are available for soap making.

The oils may be hardened or unhardened and the invention is not limited to oils which are intended for use in making soap, although the results are more significant when the 'oil is made into soap. Oils intended for edible use, such as in the manufacture of shortening, may be treated in accordance with the invention.

conventional procedure, although this is not essential for the removal of the color forming bodies. In the conventional refining of oils, for example, by the weak alkali method, the oil is heated to a temperature of about 90 C., and a weakv caustic solution is mixed therewith in an amount sufllcient to neutralize free fatty acids. The foots and the caustic are allowed to settle until a clear, sharp separation of layers can be distinguished. The foots and the caustic are then drawn off and the refined oil is washed with water by spraying the hot water into the oil, following which the water is permitted to settle and is drawn off. Usually three washings are sufficient to remove all soap from the oil. The oil is then dried at a temperature slightly above 100 C. and bleached with 2% of an acideactivated bleaching earth, at about the drying temperature. After this the oil is filtered.

The refining and earth bleaching treatments are conventional and any such may be used in the preliminary treatment of the oil. These treatments remove gums, fatty acids, certain pigments and other non-oleaginous materials. They do not affect the pink color forming bodies. It is not essential that the oil be refined and bleached before the color forming bodies are removed in accordance with the invention. We have found it possible to treat crude soybean oil, linseed and other oils according to the process described above to remove effectively the color forming impurities, and under certain circumstances the process of the invention may be applied advantageously to the crude oils without previous treatment. It is preferred, however, that the invention be practiced with refined and bleached oil.

The oil may be hydrogenated to any degree at any stage in the process, preferably after some preliminary refining, in order to harden the same and reduce the iodine value to any desired extent. The hydrogenation reduces the amount of unsaturates, and provides a stock for forming a harder soap, as is well understood in the art.

The reagents used in the treatment preferably comprise formaldehyde, such as a solution of formaldehyde, or any of the formaldehyde polymers, such as paraformaldehyde or trioxymethylene.

Examples using formaldehyde solution and paraformaldehyde have been disclosed previously. Low molecular weight aldehydes other than formaldehyde, such as acetaldehyde and paraldehyde may be used, but'they do not give as satisfactory results as formaldehyde and its polymers, and in view of the availability of formaldehyde or its polymers they are preferred.

As illustrative of the application of the inven tion to an oil other than soybean oil, bleached and hydrogenated linseed oil was treated with 1% of a 40% formaldehyde solution and 0.15% concentrated sulfuric acid for 1 hour at 65 0. Following this, the treated oil was cleaned with 2% of fullers-earth at 100" C. by stirring the earth with the oil for 15 minutes, after which the acid was neutralized and filtered. The soap made from the oil had a satisfactory white color. As contrasted with the same, bleached and hardened linseed oil was rebleached at 100 C. by stirring 2% of fullers earth with the oil for 15 minutes, following which the oil was filtered. Soap made from this oil had a pronounced pink-red color.

The oil to be treated in accordance with the invention is preferably given a preliminary refining and bleaching, in accordance with the The acid catalysts used may be any strong mineral acid, such as sulfuric acid or hydrochloric acid or acid salts thereof, such as sodium bisulfate. Other salts having an acid reaction, such as zinc chloride, may be used. These materials are recognized in the art as constituting acid catalysts for effecting resinificatlon reactions.

As illustrative of the use of hydrochloric acid as the acid catalyst, refined and bleached'soybean oil was treated with 0.25% paraformaldehyde and 0.3% of concentrated hydrochloric acid for 1 hour, at a temperature of 70 C., following which the oil was cleaned with 2% fullers earth by stirring the earth into the oil at C. for 15 minutes, and filtered. The soap produced from this treated oil has a satisfactory white color.

As illustrative of the use of sodium bisulfate as the acid catalyst, bleached and hardened soybean oil was treated in the identical manner as that just described, except that 0.3% sodium bisulfate was used in place of the concentrated hydrochloric acid. The soa made from the treated oil similarly possessed a satisfactory white color.

The amount of the reagents can be very small, in amounts otherwise are not particularly critical. In the case of the formaldehyde and its polymers, the amount required may depend, in part, on the amount of coloring materials present. In general, the smallest amount which will achieve the desired whiteness in the soap is to :be used, inasmuch as an excess is wasteful from an economic point of view and it must ultimately be removed from the oil at any event. The minimum amount can be determined readily-by routine laboratory control, such as is normally maintained in soap manufacturing operations. In general the amount can vary from 0.1 to 2% of paraformaldehyde by weight. Generally there is no advantage in using amounts larger than that indicated. Entirely satisfactory results have been obtained with 0.25%, and in instances where the color materials are not present in a larger quantity, the smaller amounts will sumce. If a formaldehyde solution is used, the amount of the solution is ad- Justed with reference to the concentration of the formaldehyde in the solution, so as to obtain the preferred amount of formaldehyde.

The amount of the acid catalyst can be exceedingly small and amounts within the range of 0.01% to 1% have been used satisfactorily. There is no point in using a larger amount of the acid catalyst than we required, since there is danger of charring the oil with a larger amount of acid at the higher temperatures employed. Exceedingly small amounts. down to a trace, may be used with satisfactory results.

A large number of samples of the same degummed, refined, bleached and hardened soybean oil were treated with different amounts of paraformaldehyde and different amounts of sulfuric acid within the above mentioned ranges. For example, degummed, refined, bleached and hardened soybean oil were treated with 2% of paraformaldehyde and 1% concentrated sulfuric acid at 85 C. The treating time was one-half hour and the settling time was one-half hour. treated material was bleached with 6% bleaching earth, such as that known by the trade name of "Special Filtrol." The. soap produced had a satisfactory white color. The process was repeated under identical conditions except that 1% of formaldehyde and 0.5% sulfuric acid was used and the soap produced was white. The process was repeated using 0.5% paraformaldehyde and 0.25% sulfuric acid and again repeated with thses proportions reversed, namely, 0.25% parai'ormaldehyde and 0.5% sulfuric acid. In each instance the soap produced from the treated oil was white. All of the soap samples prepared therefrom were satisfactory, but those employing about 0.15 to 0.25% paraformaldehyde and about 0.1 to 0.15% sulfuric acid gave the whitest soap. In view of the economic advantage involved, these small amounts are preferred.

The temperature for the treatments may be varied and the treating temperature of 50 to 110 C. is preferred. The lower limit is the temperature at which the oil or fat is liquid and of suiilcient fluidity to permit thorough agitation and mixing of the treating reagents. Although higher temperatures may be used than indicated,

ofa

there is no point in doing this, because the reaction proceeds satisfactorily in a reasonable accordance with the invention, and the amass The time at a temperature of to 85 C. and there is less danger of harming the oil at this lower temperature,

The temperature of IOU-125 C. for the earth treatment is selected because at this temperature the earth exerts a more pronounced bleach ing action along with its action in removing the excess of the reacting'ingredients and the reaction products.

The following four example are indicative of the effect of temperature: (1) Hardened soybean oil was treated with 0.25% pararormaldehyde and 0.15% sulfuric acid at a. temperature of C., and bleached with 2% Special F'iltrol for 15 minutes at a temperature of 110 C. (2) The process was repeated at a treating temperature of C. and a bleaching temperature of 120 C. (3) The process was again repeated, increasing the amount of sulfuric acid to 0.25% and using a treating temperature of 80 C. and a bleaching temperature of 120 C, (4) In the other exam- Die the treating temperature was raised to C., employing 0.5% paraldehyde and 0.25% sulfuric acid. The bleaching temperature was C. The first sample employing the lower temperatures produced an oil of the lightest color and the remaining oil samples had a darker color. The soap produced ever, was white. These results show the deleterious effect on the color of the oil when higher temperatures are used. However, the components causing the pink discolorations are removed in each instance. l

The bleaching earth is used primarily as an easy means of removing the condensed color forming bodies and only sufiicient need be used to absorb them and permit a satisfactory filtering operation. Generally, however, it is Of advantage to include enough to obtain a substantial bleaching action at the same time. Amounts within the range of 0.5 to 10% may be used, generally to 2 to 6%. Other types of clarification materials may be used, such as iullers earth, clays, infusorial earth, etc.

As illustrative of the use of diatomaceous earth for removing the reaction products formed by the treatment in accordance with the invention, crude linseed oil was treated with 0.25% paraformaldehyde and 0.15% concentrated sulfuric acid for 1 hour at 65 C. The thus treated oil was filtered through a pad of "Dicalite (diatomaceous earth). The soap made therefrom had a satisfactory color even though the original treatment is the insoluble calcium sulfate (if the acid catalyst is sulfuric acid) and this may be readily separated during the filtering operation with any excess of the unreacted insoluble chalk. There is no objection, except economic, to the use of more of the alkaline compound than required for neutralizing.

It is not essential that the oil be treated with the bleaching earth after the treatment in accordance with the invention, although the use of the bleaching earth is the most convenient means from all four samples, how-" for removing the unreacted portion of the reagents and reaction products. If desired the material may be refined after treatment in accordance with the invention. As illustrative of such a treatment, 500 parts of refined, bleached, and hardened soybean oil was treated with 1.25 parts (0.25%) of paraformaldehyde and 0.75 part (0.15%) of concentrated sulfuriciacidat a temperature of 65 C. for 1 hour with continuous a81- tation. The oil was then refined with 1% I (based on the weight of the oil) of anhydrous sodium hy-' droxide diluted to a 20% aqueous solution and the foots separated. The .dark color of the 'oil disappeared when the caustic solution was added. The soap made from the oil in a conventional soap making process did not develop'the characteristic pink color.

The time of the treatment depends largely upon the ability to effect an intimate contact between the oil and the agents used. when using refining oil kettles containing many thousand pounds of oil, it is desirable to continue the agitation over a period of from 30 minutes to several hours to insure completion of the reaction. With more thorough admixture of the ingredients, such as effected in a continuous refining process accompanied by a high degree of agitation, it is possible that the time may be reduced appreciably. There is no point in continuing the-reaction beyond the time when the improved and'wanted results are obtained.

In the preferred embodiment described in the illustrative example, the operation is carried out under a vacuum, but this is not essential and the process may be carried out at atmospheric pressure. As illustrative of the difference obtained in using a vacuum, refined, bleached and hardened soybean oil was treated with 0.25% of paraformaldehyde and 0.15% concentrated sulfuric acid for 1 hour at 65 C. under a vacuum of 6 millimeters pressure of mercury. The temperature was raised to 85 C., 2% Special Flltrol was added, the temperature was raised to 100 C., and maintained for 15 minutes with agitation.

Chalk was added to neutralize the acid and the oil was allowed to cool to 90 C. Thevacuurn was then broken and the oil was filtered. Another batch of the identical oil was treated in the identical manner, except that the entire process. was carried out at atmospheric pressure. The oil treated under the vacuum had a Lovibond color of 1.6 red and 16 yellow, (5%" column) whereas the oil treated at atmospheric pressure had a Lo-vibond color of 3.3 red and 33 yellow, (5%" column). While the oil treated under a vacuum has a lighter color the soap made from both samples had a satisfactory white color. The use of the vacuum apparently eliminates coloring materials other than the characteristic pink forming coloring materials which may be removed in accordance with. the invention irrespective of the pressure.

We are aware of the fact that it has been proposed heretofore totreat oils and fats with formaldehyde or paraformaldehyde in the presence of zinc dust or iron filings and sulfuric acid. The latter reacts with the metal to generate hydrogen and the nascent hydrogen reduces the formaldehyde to its alcohol which is then removed. The reduction of formaldehyde to its alcohol would prevent the removal of coloring materials of the type contemplated in accordance with the invention. Our invention has revealed an unobvlous fact that apparently the use of formaldehyde or its polymers as such in the presence of an acid 8 catalyst removes materials which apparently do not color the oil per se but which form color materials during saponification so that the soap takes on an objectionable color.

It will be obvious to those skilled in. the art that the invention is capable of operation with" a variety of reacting ingredients within the groups disclosed herein, and that a wide variety of conditions and processing procedures other than that described as the preferred embodiment are adapted to existing equipments and technique. All such variations are intended to be within the invention as fall within the scope of the following claims.

A reference in the following claims to formaldehyde, otherwise unqualified, is intended to refer to it in a. gaseous, solution or polymer form, any of which may be used. Oleaginous glyceride is used to refer to the triglyceride type of oil and fat. Fatty materialis used as generic to fatty acids or glycerides thereof. A reference to a glyceride or an oil is intended to include both an oil, either hardened or unhardened, which contains free fatty acids, or an oil which has been freed from free fatty acids by neutralization with caustic alkalies. A reference to a specific oil, such as soybean oil, is intended to include the oil both in its unhardened and its hydrogenated or hardened form.

We claim:

1. The process of improving oleaginous glyceride oil and fat stock, which comprises the step of treating said stock to remove color imparting impurities therefrom by adding to the stock and contacting it with treating agents consisting of.

formaldehyde and a mineral acid catalyst.

2. A process of improving oleaginous stocks whichproduce a distinct coloration in soap made therefrom, which comprises the step of treatin said stock to remove color imparting impurities therefrom by adding to the stock and contacting it with treating .agents consisting of a small amount of formaldehyde and a small amount of a mineral acid catalyst, and removing any of the unreacted treating reagents and reaction products of the stook ingredients therewith.

3. A process of improving oleaginous stocks which produce a distinct coloration in soap made therefrom, which comprises the step of treating said stock to remove color imparting impurities therefrom by adding to the stock and contacting it with treating agents consisting of a small amount of formaldehyde and a small amount'oi a mineral acid catalyst, and removing any of the unreacted treating reagents and reaction products of the stock ingredients therewith by treat: ment with ,a bleaching earth.

4. A process of improving oleaginous stocks which produce a distinct coloration in soap made therefrom, which comprises the step 'of treating said stock to remove color imparting impurities therefrom by adding to the stock and contacting it with treating agents consisting of a small amount of formaldehyde and a small amount of a mineral acid catalyst, and removing any of the unreacted treating reagents and reaction products of the stock ingredients therewith by alkali refining.

5. A process of improving oleaginous stocks, which comprises the step of treating said stock to remove color imparting impurities therefrom by adding to the stock and contacting it with treating agents consisting of about 0.1 to 2.0% of formaldehyde and about 0.01 to 1.0% of a mineral acid catalyst, and removing the reaction 9 products of the treating reagents with the stock ingredients by absorption in a bleaching earth.

6. A process of improving oleaginous stocks which produce a distinct coloration in soap made therefrom, which comprises the step of treating said stock to remove color imparting impurities therefrom by adding to the stock and contacting it with treating agents consisting of about 0.1 to 0.5% of paraformaldehyde, and about 0.01 to 0.25% of sulfuric acid, at a temperature to maintain the stock liquid, and removing the reaction products of the treating reagents with. the stock ingredients by absorption in a bleaching earth.

7. The process which comprises adding to soybean oil and contacting it with treating agents consisting of paraformaldehyde and sulfuric acid.

8. A process of treating soybean oil which comprises admixing said oil with treating agents consisting of a small amount of'formaldehyde and a small amount of a mineral acid catalyst, adding thereto and mixing therewith a bleaching earth at a bleaching temperature, and filtering the oil.

9. A process of treating soybean oil which comprises admixing said oil with treating agents consisting of a small amount of formaldehyde and a small amount of a strong mineral acid at a temperature of about 50 to 110" C., adding thereto a, bleaching earth and mixingat a bleaching temperature, neutralizing any remaining acid, and

filtering the oil.

10. A process of treating soybean oil which comprises admixing said oil with treating agents consisting of a small amount of paraformaldehyde and a small amount of sulfuric acid at a temperature of about 60 to 85 C., adding thereto and mixing therewith about 1 to 6% of a bleaching earth at a temperature of 85 to 125 C. and filtering the oil.

11. A. process of treating soybean oil which comprises admixing said oil with treating agents consisting of a small amount of paraformaldehyde and a small amount of sulfuric acid at a temperature of about 60 to 85 C., adding thereto about 1 to 6% of a bleaching earth and mixing at a temperature of 85 to 125 C., neutralizing any remaining acid with chalk, filtering the oil, and saponifying the same to make soap therefrom free from the color normally characteristic of soybean oil soap.

12. A process of treating soybean oil which comprises admixing said oil with treating agents consisting of 0.1 to 2% of paraformaldehyde and 0.01 to 1% of sulfuric acid at a temperature of about 60 to 85 C., adding thereto about 2% of a bleaching earth and mixing at a temperature of 10 about 100 to 110 C., neutralizing any remaining acid with chalk, filtering the oil, and saponifying the same to make soap therefrom free from the color normally characteristic of soybean oilsoap.

13. A process of treating hardened soybean oil which comprises admixing said oil with treating agents consisting of about 0.25% of paraformaldehyde and about 0.15% of sulfuric acid at a temperature of about C., adding thereto about 2%. of a bleaching earth and mixing at a temperature of about 100 C., neutralizing any remaining acid with chalk, filtering the oil, and saponifying the same to make soap therefrom free from the color normally characteristic of soy.- bean oil soap.

14. The process which comprises adding to linseed oil and contacting it with treating agents consisting of paraformaldehyde and sulfuric acid.

15. A process of treating linseed oil which comprises admixing said oil with treating agents consisting of a small amount of formaldehyde and a small amount of a mineral acid catalyst, adding thereto and mixing therewith a bleaching earth at a bleaching temperature, and filtering the oil.

16. A process of treating linseed oil which com prises admixing said oil with treating agents consisting of a small amount of paraformaldehyde and a small amount of sulfuric acid at a temperature of about 60 to C., adding thereto and mixing therewith about 1 to 6% of a bleaching earth at a temperature of 85 to 125 C. and filtering the oil.

1'7. A process of treating hardened linseed oil which comprises admixing said oil with treating agents consisting of 0.1 to 2% of paraformaldehyde and 0.01 to 1% of sulfuric acid at a temperature of about 60 to 85? C., adding thereto about 2% of a bleaching earth and mixing at a temperature of to C., neutralizing any remaining acid, filtering the oil, and saponifying the same to make soap therefrom free from the color normally characteristic of linseed oil soap.

LLOYD F. HENDERSON. LOUIS H. LIBBY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,744,843 Taylor Jan. 28, 1930 1,104,906 Lach July 28, 1914 856,357 Metz June 11, 1907 

